Quantity   Component name
1 × Sparkfun Pro Mico This is a very small micro-controller. It fits neatly inside our watch enclosure. It is not an official Arduino board, but it is Arduino compatible. That basically means you have to do a little extra setup before you can program it via the Arduino IDE. The process is pretty straight foreword.
1 × 850mAh Lithium Ion Battery
1 × 110mAh Lithium Ion Battery
1 × Power Cell (Lipo Charger/Booster) Our battery outputs 3.7V. The Pro Micro board requires a 5V power source. The power cell is used to boost the 3.7V output to 5V for the Pro Micro. The battery hooks into the power cell using a standard JST connector. The power cell provides a convenient micro-USB connector that can be used to charge the battery. We expose this connector on the side of the enclosure so that the watch can be recharged without removing the lid.
1 × SPDT Mini Power Switch The on/off switch exposed on the outside of the watch enclosure.
1 × Monochrome 128×32 SPI OLED graphic display This is a great little OLED display. Adafruit makes it pretty easy to work with as well via their libraries and tutorials.
2 × XBee 2mW PCB Antenna (Series 2)
1 × Fio v3 (ATmega32U4) This is another Arduino compatible micro-controller produced by Sparkfun. It is very similar to the Pro Micro used in the wristwatch. Again there is some light setup, but that’s covered in the same guide linked to above. One great feature of this board is that is has a XBee socket built right in. This eliminates the need to wire up the XBee separately and find a way to secure it inside the enclosure. It only requires a 3V input and it has an integrated LiPo charger eliminating the need for something like the power cell used in the wristwatch. The main reason the wristwatch uses the Pro Micro over the Fio is size. The Fio is not big by any means, but it is longer than the Pro Micro and we did not want to enlarge the watch enclosure to accommodate it.
1 × Force Sensitive Resistor
1 × Terminal Block (2-pin 3.5mm)